Our focus on instructional time loss as an indicator of educational opportunity is grounded in a
long-standing body of research on the importance of learning time. A half century ago, John
Carroll placed time at the center of his model for school learning. Carroll’s commonsense notion
was that what students learn is related to the time they spend learning.1 A great deal of
subsequent research has confirmed Carroll’s central insight: learning time matters.
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Summarizing this research, David Farbman, a researcher at the National Center on Time and
Learning, notes that more time enables teachers to “cover more material and examine topics in
greater depth and in greater detail, individualize and differentiate instruction, and answer
students’ questions.”